Listen carefully and you'll hear the death rattle of traditional advertising, as some of its practitioners embrace a desperate and cynical idea called low-involvement processing (LIP).

LIP was the subject of a monograph published by Admap, the publication of the World Advertising Research Center in England, written by Robert Heath of The Value Creation Company.

LIP draws on studies in neuroscience that suggest the human mind is constantly at work, filtering information from numerous sources every second. While humans are only conscious of a tiny proportion of these messages, even those we don't notice ourselves noticing might offer context for many of the decisions we later make quite consciously.

Advertising works best, says Heath, when it slips under the radar.

"Consumers do not expect to learn anything of real importance about brands from advertising and are, therefore, not predisposed to pay much attention to it," he suggests in The Hidden Power of Advertising. "Brand information tends not so much to be actively sought after as passively acquired."

Heath recommends stuffing ads full of "emotional markers" that "convey powerful, hidden meanings, which insidiously influence the way we choose brands ... without consumers realizing it." What he does not suggest is creating interesting, eye-catching ads that cut through the clutter. It's far better for ads to remain part of the background noise, he says.

Not surprisingly, these ideas have generated controversy, especially in the UK, where LIP has gained most traction. The idea hasn't been embraced by creative types, and it's not particularly popular among those who argue that recall is the best measure of advertising's effectiveness. Others worry that Heath's theories could be used by critics of advertising: LIP sounds a lot like the sinister subliminal messaging that raised concerns in the '90s.

Still, some have welcomed the ideas: "There is hope on the horizon," said DDB Worldwide chief executive Ken Kaess in a speech two years ago. "Curiously, low involvement does not translate to low impact. It simply means that the way advertising works on people is much subtler than copy tests would have us and our clients believe."

Heath admits that LIP might not work for brands that really do have something new and interesting to say - he doesn't actually recommend PR as the best way to promote such products, but the conclusion is obvious. Ultimately, though, the rise of LIP is most interesting for what it says about advertising in general: that it's a poor tool for building any kind of meaningful relationship with consumers. It's increasingly obvious that's a job best left to PR.

Paul Holmes has spent the past 17 years writing about the PR business for publications including PRWeek, Inside PR, and Reputation Management. He is currently president of The Holmes Group and editor ofwww.holmesreport.com.